This invention relates to a process for the production of yarns, and more particularly, for the production of slub yarns. Slub yarns are well known to the art. The process of the present invention, however, provides a slub yarn in a continuous process without employing any additional mechanical apparatus to produce the slub as is normally required by the prior art. In particular, the present invention provides a randomized slub effect which is not possible with the prior art.
In U.S. Pat. Nos. 2,997,837 and 3,043,087 a slub yarn and the process for preparing the yarn are shown. In this process an effect yarn or staple is added as a slub to a continuous carrier yarn. The cranking action of the carrier yarn as it enters a fluid twister is used to pull along the effect staple fibers or the continuous effect yarn. Passing the combined yarns or yarn and staple fibers through the fluid twister serves to wrap the effect yarn more permanently about the carrier. The slubs are characterized by being wrapped about the carrier yarn with both an S twist and a Z twist.
In U.S. Pat. No. 3,438,194, a process for the production of a slub yarn is shown. Like the yarn of the present invention, this slub yarn consists of two or more components; at least one carrier yarn and one or more effect yarns. However, unlike the present invention, this process involves varying the feed rate of at least one of the component yarns. Specific apparatus is disclosed for the purpose of varying this feed rate.
U.S. Pat. No. 3,640,064 shows a slub yarn which is also produced by intermittently relieving the tension of one of two multi-filament yarns as they are fed simultaneously into a fluid bulking jet.
U.S. Pat. Nos. 4,155,216 and 4,159,619 show a slub yarn and the method of producing the yarn. The yarn is prepared by mechanically tensioning and relaxing the yarn while it passes through a fluid tangling zone.
It is an object of the present invention to provide a slub yarn in which slubs of one or more continuous effect yarns are added to one or more carrier yarns without the necessity of providing means to mechanically vary the tension in one of the yarns.
It is a further object of the present invention to produce a yarn with a randomized slub effect.
According to the present invention there is disclosed a method of producing a slub fiber comprised of at least one core yarn and at least one effect yarn comprising the steps of feeding an effect yarn directly into the balloon formed by the core yarn at the exit of the vortex generator while maintaining on said effect yarn a low, but continuous and relatively constant tension, and to allow said effect yarn freedom to make contact at a random point on the balloon, to spontaneously form a slub.
This invention will be understood from the following detailed description and the accompanying drawings.